I would suggest the fuse as well. Perhaps the motor is seated too high and jamming the gearbox?
Personally, my CA M15 rifle has been very reliable to date. I've put about 10 000 rounds through it without any issues to date. No misfeeds, jams, etc. I know CA pistons and piston heads are prone to failiure, so I have a Systema piston, piston head and cylinder set waiting to be installed as soon as I see the first sign of trouble. But to date, no issues.
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